Countersinking tool



April 24, 1945- M. F. MAR|N| I 2,374,552

. COUNTERSINKING TooL Filed July 15, 1944 IN VEN TOR.

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Patented Apr. 24, 1945 UNITED STATES PATENT 'OFFICE l QOUNTERSNKINGTOOLl Mario F. Marini, Swedesboro, N. J. Application `July 15, 1944,Serial No. 545,031 2 claims. (c1. w-ras) The pre-sent invention relatesto countersinking tools or reamers and it relates more particularly to anewand improved countersinking tool or broaching bit.

An object of the present invention is to provide a new and improvedcountersinking tool or reamer or broacher. Another object of the presentinvention is to provide a new and improved countersinking tool or reameror broacher which will be positively guided in the hole being worked.

Other objects and advantages of the present invention rwill be apparentin the following vdetailed description, appended claims andaccomlpanying drawing.

lng the countersinking operation so that the bevel formed very often isnot uniform and is offcenter Arelative to the axis of the hole.

Accordingly, the present invention contemplates a new and improvedcountersinking tool or' reamer or broacher which will be positivelyguided axially of the hole so that the final bevel formed will belaccurate and properly centered.

Generally speaking. the present invention cornprehends a cuntersinkingtool having inclined cutting-edges of appropriatetaper and having aguide detachably connected forward of the cutting-edges; the guide beingadapted to t Within the hole with slight clearance so as to preventwobbllng or other lateral movement of the cutting-edges during thecountersinking operation. The present invention further contemplates theuseof a plurality of diiTerent-diametered guides whereby the samebroacher can be used for different-sized holes. For the purpose ofillustrating the invention,

there are shown in the accompanying drawing forms thereof which are atpresent preferred, since the same haveA been found in practice to givesatisfactory and reliable results, although it is to be understood thatthe various instrumentalities 4oi' which the invention consists can bevariously arranged and organized and that the invention is not limitedto the precise arrangement/s and organizations of the instrumentalitiesas herein shown and described.

Referring to the accompanying drawing in which like reference charactersindicate like parts throughout:

Figure l represents a perspective view of one embodiment of the presentinvention as it appears in'uSeI Darts being broken away better to revealthe construction thereof.

Figure 2 represents an exploded elevational view of the embodiment ofFigure l.

Figure 3 represents a bottom plan view of the countersinking tool ofFigure 2, as it appears when the guide and nut are removed.

Figure 4 represents a view partly in perspective and partly incross-section of the guide of Figures 1 and 2.

Figure 5 represents a fragmentary view partly in elevation and partly incross-section showing the countersinking tool of Figure l as it appearsin use inra larger-diametered hole and with a larger-diametered guide.

Figure 6 represents a fragmentary view partly in elevation and partly incross-section showing another embodiment of the present invention as Ygripped by .the chuck I3 Vof a drill-press or the like (not shown).

A plurality l for example four) of taperedcutting-edges Il are formed atthe lower end of the body portion II;the cutting-edges Il being relievedas at I5 in conventional manner.

A post I6 extends from the forward or lower face Il of the body portionII generally (along the axis of said counterbore III. The post I6 (whichha's a relatively small transverse dimension) has a square (or othernon-circular) stem portion I8 which is nearest the body portion II andan externally screw-threaded stern portion I9 formed at the outer end ofthesquare portion i8; the sides of the square portion I3 being formed asgenerally tangential extensions of the screw-threaded portion I9 asshown particularly in Figure 3.

A generally cylindrical guide 20 is adapted to be removably mounted uponthe post I6 of the counterbore I 0. tured; the .aperture having a squarecross-section as at 2| (adapted to fit snugly about the square portionI8 of the post i6) andhaving a circular cross-section at itslower orouter end as at 22 (adapted to t about the screw-threaded portion I9 ofsaid post I6 with a slight clearance).

The guide 20 has an axial dimension somewhat less than the length of thepost I6 so that, when the guide is tted upon the post. enough of thescrew-threaded portion I9 of saidA post I E Vwill protrude to permit anut 23 to be screw-threadedly mounted thereon to lockthe guide 20 inposition as shown in Figure l.` In the embodiment of Figures l to 5, theguide 2li has a diameter generally the same as the baximum diameter ofthe lower face I'I of the counterbore I0; this diameter being veryslightly less than the diameter of. the opening to be countersunk.

The guide 20 is axially aper- Thus, when the countersinking tool of thepresent invention is inserted Iwithin the hole or openv ing 24 to beroamed or broached or countersunk as shown in Figure l. the guidethereof will fit snugly within said opening 24 with relatively slightIclearance. Thus, the forward or Working end of the countersinking toolwill be kept from -4 wobbling or other undesirable lateral movement orshifting during-the countersinking operation and will be maintained inIposition generally axially of the opening so that the bevelformedthereby will be accurate anduniform throughout.

- It is apparent that the counterbore Illof Figure l can be used tocountersink aplurality of different-'diametered openings due to theupward and outward ilare of the cutting-edges I4. That is, withrelatively smaller-diametered openings (i. e. openings only slightlylarger in diameter than the lower face Il), the bevel will be formed bythe lower smaller portions of the cutting edges Iii while withrelatively larger-diametered'openings (i. e. openings slightly smallerin diameter than the maximum diameter of the body portion I I), thebevel will be formed by the larger upper vmost portions of the cuttingedges I4.

Thus, where the countersinking tool is to be used in the relativelysmallerdiametered`open ing 24 as stated hereinabove, the guide employedwill be like that shown in Figures l, 2, and 4; that is, a guide havinggenerally the same diameter as the lower face I1 as stated'hereinaboveWhen, on the other hand, vthe countersinking l' ting-edges may be madewith a 60 taper as shown in the drawing or, instead, may be made with a45 taper or a 65 taper or any other desired taper. The number ofcutting-edges and the shape thereof may also be varied through widelimits depending upon the type of operation to be done and the nature ofthe 'materialto be worked.

- The countersinking tool of thepresent invention, when used with aproper-diametered guide.

ispositively centered in the opening and insures an-even chamfer orbevel and even removal of burrs regardless of whether it is manipulatedby adrillpress or a brace-and-bit or any other suitable tool.

tool is intended to be used in a' larger-diametered Opening 24a -asshownin Figure 5, a. Ingen diametered guide 2li-a is employed; the guide 20-ahaving a diameter greater than that of the face il and slightly lessthan that of the openf.

ing 24-a so that, again, the countersinking tool is maintained in properaxial alignment with the opening during the forming of the bevel by theupper portions of the cutting-edges I4.

In Figure 6 I have shown another embodiment of the present invention.The embodiment of Figure 6- includes a counterbore I Ila having a bodyportion iia, cutting edges Il a and a lower` face ii-a similarto thosedescribed in .connection with the embodiment oi Figure 2 but having anaxial post 2E .extending downwardly from the face i'i-a. The post 25 isexternally screw-threaded generally through its length with a right-handthread.

Upon the post 25 there tachably mounted a guide 26 which is providedwith an axial internally screw-threaded opening adapted'to receive saidpost 25. It is apparent that right-hand rotation of the countersinkingtool during the counterboring operation will tend to tighten the 'guide26 upon the post 25.

While the guide 2S of Figure 6 has a diameter generally the same as thatoi the lower face I'i-a,

' so that the countersinking tool is adapted for use withthesmaller-diametered opening 24 as shown lin Figure 6, it is apparent thatthe guide 26 could be made with a larger diameter to permit thecountersinking tool to be used in the larger-diametered opening 24a. i.

The novel countersinking tool of the present invention is adaptedquickly and easily to form bevels or chamfers in openings as describedhereinabove and also to remove burrs on the inner edge of holes such asmight be formed, for. ingstance, in cutting pipes orthe like.

The size and vshape of the cutting-edges can be varied considerably.Thus, for example, the Cutlis adapted to be de' cylindrical The presentinvention may be embodied in other specic forms without departing fromthe spirit or essential attributes thereof, and it is thereforeA desiredthat the present embodiments be consid--v ered inall respects asillustrative' and not reof circumferentially-spaced taperedcutting-edges formed at the forward end of said body portion, saidcutting-edges being adapted to form a bevel 'at the end of a hole or thelike when said tool is axially rotated,l a reduced post extendingaxially -from the forward" end of said body portion, said *post having anon-circular portion, a generally centering-guide adapted non-rotatablyto t over said non-circular portion, .and'means for fastening saidcenteraxially-apertured ing-guide upon said post, said centering-guidebeing adapted to enter said hole ahead of said cutting-edges and havinga diameterrslightly less than that of the hole, whereby itwill'centersad tool generally axially of said hole during the cuttingoperation and will tend topreventlateral shifting of said cutting-edges.

2. A countersinking tool or the like comprising a generally cylindricalbody portion, a reduced shank extending axially rearward from said bodyportion and adapted to be gripped by a chuck or the like for rotation ofsaid tool, a plurality of circumferentially-spaced tapered cutting-edgesformed at the forward end of said body portion, said cutting-edges beingadapted to form a bevel at the end of a hole or the like when said toolis axially rotated, a reduced post extending axially from the forwardend of said body-portion', said post having a generally polygonalcross-section adjacent said body portion and being screwthreaded -at itsouter end, a generally cylindrical axially-apertured centering-guideadapted nonrotatably to t over the polygonal vportion of said post, anda" nut adapted screw-threadedly to engage with the end of said post andto lock said centering-guide thereon,` said centering-guide` beingadapted to enter said hole ahead of said cutting-edges and having adiameter slightly less than that of the hole, whereby it will centersaid tool" generally axially of said hole during a cutting operation andwill tend to prevent lateral shifting of said cutting-edges.

MARIO F. MARINI.

